1. Field of Invention
The present invention relates to thin-film forming devices for forming thin films by applying a coating solution onto a substrate, thin-film forming methods, devices for manufacturing liquid crystal displays, methods for manufacturing liquid crystal displays, devices for manufacturing thin-film structures, methods for manufacturing thin-film structures, liquid crystal displays, thin-film structures, and electronic apparatuses. In particular, the present invention relates to a preferable device and method capable of easily and accurately controlling the thickness of a thin-film.
2. Description of Related Art
Currently, a spin coating method used as one of techniques for forming thin films is a method for forming a thin film by dripping a coating solution onto a substrate and subsequently applying the coating solution over the entire substrate using a centrifugal force generated by rotating the substrate. In this method, the film thickness is controlled by a rotation speed, a rotation time, and viscosity of the coating solution. This spin coating method has been widely used, for example, for the formation of photoresist films or interlayer insulating films such as SOG (spin on glass) in a semiconductor manufacturing process or the like. The method has also been used in the formation of alignment films in a process for manufacturing liquid crystal displays or the like, and the formation of protection films in a process for manufacturing optical discs or the like.
In this spin coating method, since most of the coating solution thus supplied is scattered, a large quantity of the coating solution must be supplied, and at the same time, the waste thereof is large, resulting in disadvantageous increase in cost. In addition, since the substrate is rotated, the coating solution flows from the inside to the outside due to a centrifugal force, and as a result, the thickness at the peripheral region tends to be thick as compared to that at the inside region, resulting in problem of uneven film thickness. As measures against the disadvantages described above, in recent years, a coating method using a so-called inkjet technique has been proposed.
For example, in Japanese Unexamined Patent Application Publication Nos. 9-10657, 8-196983, and 9-192573, techniques have been disclosed in which a rotation technique for rotating a substrate is provided. In these techniques, a coating solution ejected onto the substrate by a droplet ejection head is moved by the rotation movement of the substrate, and the thickness of a thin film made of the coating solution is controlled by changing the rotation speed of the substrate, rotation time, and the like.